Number Of Wasps Research Articles

Impact of the parasitic wasp Nasonia spp. (Walker, 1836) Hymenoptera: Pteromalidae) on populations of bird blowflies Protocalliphora spp. Hough, 1899 (Diptera: Calliphoridae)

In this work we focused on the prevalence of infection of Nasonia spp in pupae of Protocalliphora spp collected from nests n of different avian hosts from different sites in Slovakia Our research was focused on the impact of this parasitoid wasp on bird blowflies under natural conditions We studied its occurrence which was of all nests where bird blowflies were present The consequent mortality of host populations was with the number of wasps localized in individual pupa estimated on almost The aim of this work was to show that parasitoid wasp Nasonia spp significantly affects populations of Protocalliphora spp under natural conditions and that they have important role in regulation of population of bird blowflies

Identifying native plants for coordinated habitat management of arthropod pollinators, herbivores and natural enemies

Abstract Providing noncrop flowering resources in agricultural landscapes is widely promoted as a strategy to support arthropods that deliver pollination and pest control services. However, management options have largely been developed separately for pollinators and natural enemies, whereas possible effects on insect herbivores, such as crop pests, have often been overlooked. A first critical step for design and implementation of multifunctional plantings that promote beneficial arthropods while controlling insect pests is to identify suitable plant species to use. We aimed to identify California native plants and, more generally, plant traits suitable for the coordinated management of pollinators (wild bees and honeybees), insect herbivores and arthropod natural enemies (predators and parasitic wasps). We established 43 plant species in a common garden experiment and sampled arthropods by weekly netting (wild bees), observations (honeybees), or vacuum sampling (insect herbivores, arthropod predators, and parasitic wasps) during peak bloom of each plant species over 2 years. Plant species differed in attractiveness for each arthropod functional group. Floral area of the focal plant species positively affected honeybee, predator, and parasitic wasp attractiveness. Later bloom period was associated with lower numbers of parasitic wasps. Flower type (actinomorphic, composite, or zygomorphic) predicted attractiveness for honeybees, which preferred actinomorphic over composite flowers and for parasitic wasps, which preferred composite flowers over actinomorphic flowers. Across plant species, herbivore, predator, and parasitic wasp abundances were positively correlated, and honeybee abundance correlated negatively to herbivore abundance. Synthesis and applications. We use data from our common garden experiment to inform evidence‐based selection of plants that support pollinators and natural enemies without enhancing potential pests. We recommend selecting plant species with a high floral area per ground area unit, as this metric predicts the abundances of several groups of beneficial arthropods. Multiple correlations between functionally important arthropod groups across plant species stress the importance of a multifunctional approach to arthropod habitat management.

The effects of introduced vespid wasps (Vespula germanica and V. vulgaris) on threatened native butterfly (Oreixenica ptunarra) populations in Tasmania

Introduced vespid wasps (Vespula germanica and V. vulgaris) are highly efficient predators of native invertebrates. They have the potential to reduce populations of threatened species and change ecosystem dynamics, yet their impact is largely unknown in Australia. The introduction of vespid wasps has coincided with a decline in numbers of threatened Ptunarra brown butterflies (Oreixenica ptunarra) in Tasmania, Australia. The Ptunarra brown butterfly is endemic to Tasmania, where its habitat has been fragmented by clearance for agriculture and forestry. Local extinctions of the species were previously thought to be principally due to its inability to fly the long distances between habitat patches in this disjointed landscape. We investigate the importance of the new threat of vespid wasp predation in the decline of O. ptunarra in the highland grasslands of northwest Tasmania. Numbers of O. ptunarra analysed over a period of 15 years dramatically declined after the arrival of vespid wasps. Wasp control was trialled to determine whether it affected butterfly numbers. Current control methods decreased wasp numbers considerably, resulting in a small increase in butterfly numbers, indicating that wasp predation is keeping O. ptunarra at low densities. Without ongoing conservation measures, it is likely that butterfly numbers will stay low, potentially leading to genetic bottlenecks and more local extinctions. An increase in the intensity of wasp control, in combination with other conservation management methods, is required for the protection and recovery of O. ptunarra.

Phylogenomic analysis of Apoidea sheds new light on the sister group of bees

BackgroundApoid wasps and bees (Apoidea) are an ecologically and morphologically diverse group of Hymenoptera, with some species of bees having evolved eusocial societies. Major problems for our understanding of the evolutionary history of Apoidea have been the difficulty to trace the phylogenetic origin and to reliably estimate the geological age of bees. To address these issues, we compiled a comprehensive phylogenomic dataset by simultaneously analyzing target DNA enrichment and transcriptomic sequence data, comprising 195 single-copy protein-coding genes and covering all major lineages of apoid wasps and bee families.ResultsOur compiled data matrix comprised 284,607 nucleotide sites that we phylogenetically analyzed by applying a combination of domain- and codon-based partitioning schemes. The inferred results confirm the polyphyletic status of the former family “Crabronidae”, which comprises nine major monophyletic lineages. We found the former subfamily Pemphredoninae to be polyphyletic, comprising three distantly related clades. One of them, Ammoplanina, constituted the sister group of bees in all our analyses. We estimate the origin of bees to be in the Early Cretaceous (ca. 128 million years ago), a time period during which angiosperms rapidly radiated. Finally, our phylogenetic analyses revealed that within the Apoidea, (eu)social societies evolved exclusively in a single clade that comprises pemphredonine and philanthine wasps as well as bees.ConclusionBy combining transcriptomic sequences with those obtained via target DNA enrichment, we were able to include an unprecedented large number of apoid wasps in a phylogenetic study for tracing the phylogenetic origin of bees. Our results confirm the polyphyletic nature of the former wasp family Crabonidae, which we here suggest splitting into eight families. Of these, the family Ammoplanidae possibly represents the extant sister lineage of bees. Species of Ammoplanidae are known to hunt thrips, of which some aggregate on flowers and feed on pollen. The specific biology of Ammoplanidae as predators indicates how the transition from a predatory to pollen-collecting life style could have taken place in the evolution of bees. This insight plus the finding that (eu)social societies evolved exclusively in a single subordinated lineage of apoid wasps provides new perspectives for future comparative studies.

Responses of Anastrepha suspensa, Diachasmimorpha longicaudata, and Sensitivity of Guava Production to Heterorhabditis bacteriophora in Fruit Fly Integrated Pest Management.

Caribbean fruit fly, also known as Caribfly or Anastrepha suspensa , is a major tephritid pest of guavas. A virulent entomopathogenic nematode (EPN) species was investigated to suppress the fruit-to-soil stages of Caribflies, which are also attacked by the koinobiont parasitoid Diachasmimorpha longicaudata in south Florida. The main objective was to develop a feasible and cost-effective EPN-application method for integrated pest management (IPM) of Caribfly to improve guava production. Naturally infested guavas were treated with increasing Heterorhabditis bacteriophora infective juvenile (IJ) concentration or rate (0, 25, 50, …, 1,600 IJs cm -2 ) in field trials to measure the optimum IJ rate and then examine sensitivity of producing guavas to inclusion of Heterorhabditis bacteriophora in Caribfly IPM plans. Relative survival of Caribfly in treatments significantly decreased with increasing IJ rate from 0 to 100 IJs cm -2 . Similarly, probability of observing large numbers of parasitoid wasps ( Diachasmimorpha longicaudata ) in EPN treatments significantly declined with increasing IJ rate (0-100 IJs cm -2 ), even though the non-target effects of Heterorhabditis bacteriophora on relative survival of Diachasmimorpha longicaudata could not be determined because of few emerging parasitoid wasps. Optimum suppression (⩾ 60%) of Caribfly was consistently achieved at 100 IJs cm -2 or 17,500 IJs fruit -1 . Profitability analysis showed that Heterorhabditis bacteriophora can be included in Caribfly IPM tactics to produce guavas. Costs of EPNs in Caribfly IPM are minimized if Heterorhabditis bacteriophora is strategically applied by spot treatment of fruit. Repayment of costs of EPN-augmentation by spot treatments appears achievable by recovering 5.71% of the annual yield losses (⩾1,963 kg ha -1 ≈ US$ 8,650 ha -1 ), which are largely due to Caribfly infestation. Hectare-wide EPN-augmentation (or broadcasting) method requires more fruit recovery than the total annual yield losses to repay its high costs. Profitability of guava production in south Florida will not be very sensitive to marginal costs of the spot treatment method, when compared to the field-wide broadcasting of Heterorhabditis bacteriophora .

Where should I lay my eggs? Oviposition choices of a shelter‐building moth and the shifting danger of being parasitized

AbstractYoung unable to move freely depend on their parents to place them in sites with superior resources or protection from unfavorable factors. The preference‐performance hypothesis holds that females should oviposit on sites that maximize the performance of their offspring. Shelters may provide their inhabitants with superior food resources, protection from enemies, and ameliorated physical factors. Accordingly, one might predict that females would prefer shelters to alternatives, since they might provide enemy‐free space. However, Herpetogramma theseusalis (Walker) (Lepidoptera: Crambidae) fern moths oviposited both in shelters constructed on sensitive ferns (Onoclea sensibilis L., Dryopteridaceae) and on exposed fern pinnae, perhaps as a bet‐hedging tactic. The moths laid eggs on the outer parts of the shelters, but after hatching the young caterpillars moved toward the center of the shelters, often beyond the reach of their common larval parasitoid, Alabagrus texanus (Cresson) (Hymenoptera: Braconidae). Although caterpillars in both areas grew at the same rate, those in shelters were parasitized less frequently than those on exposed pinnae. However, shelters senesced from the center to the periphery, depriving the caterpillars of progressively more of their food source and eventually forcing them into the open, potentially increasing their vulnerability. But numbers of wasps decreased simultaneously; hence, most caterpillars were not exposed until danger from the parasitoids had greatly diminished. Thus, offspring of females ovipositing in shelters experienced superior success, consistent with the preference‐performance hypothesis, but through lowered mortality via use of enemy‐free space, rather than superior feeding conditions.

Effect of induced tolerance to Bt toxin on the egg size of Helicoverpa armigera and parasitism by Trichogramma pretiosum

AbstractLarvae of Helicoverpa armigera (Hübner) can develop a form of Bt tolerance after exposure to sub‐lethal doses of Bt‐toxin subclass Cry1Ac. Increasing levels of tolerance are produced over generations of larval exposure, which are not related to DNA sequence changes, and are largely maternally transmitted. The characteristic of maternal transmission, combined with the importance of egg parasitoids to cotton pest management, raises questions about the effects of Bt tolerance/exposure on the eggs of H. armigera and on some key metrics of egg parasitism. In the present study, the effect of inducible tolerance on eggs of H. armigera and parasitism by Trichogramma pretiosum (Riley) is investigated. First, the volumes of eggs laid by susceptible and tolerant H. armigera females are compared. In addition, the effect of inducible tolerance on egg parasitism is determined by comparing parasitism success, the number of adult wasps emerged per host egg, and the proportion of male and female offspring emerged per host egg. The results obtained suggest that Cry1Ac‐tolerance is associated with increased egg volume, even after just one generation of sub‐lethal exposure. When tolerant H. armigera are freed from ongoing sub‐lethal exposure, a corresponding decrease in egg volume is not detected. Although there is no difference in the percentage of eggs parasitized, there is an increase in the number of emergent parasitoids, especially males, from eggs laid by tolerant H. armigera. These results confirm that maternally‐transmitted Bt tolerance is reflected in the phenotype of the eggs of tolerant offspring, which affects egg parasitism.

Social Learning in Vespula Germanica Wasps: Do They Use Collective Foraging Strategies?

Vespula germanica is a social wasp that has become established outside its native range in many regions of the world, becoming a major pest in the invaded areas. In the present work we analyze social communication processes used by V. germanica when exploiting un-depleted food sources. For this purpose, we investigated the arrival pattern of wasps at a protein bait and evaluated whether a forager recruited conspecifics in three different situations: foragers were able to return to the nest (full communication), foragers were removed on arrival (communication impeded), or only one forager was allowed to return to the nest (local enhancement restricted). Results demonstrated the existence of recruitment in V. germanica, given that very different patterns of wasp arrivals and a higher frequency of wasp visits to the resource were observed when communication flow between experienced and naive foragers was allowed. Our findings showed that recruitment takes place at a distance from the food source, in addition to local enhancement. When both local enhancement and distant recruitment were occurring simultaneously, the pattern of wasp arrival was exponential. When recruitment occurred only distant from the feeder, the arrival pattern was linear, but the number of wasps arriving was twice as many as when neither communication nor local enhancement was allowed. Moreover, when return to the nest was impeded, wasp arrival at the bait was regular and constant, indicating that naive wasps forage individually and are not spatially aggregated. In conclusion, this is the first study to demonstrate recruitment in V. germanica at a distance from the food source by modelling wasps’ arrival to a protein-based resource. In addition, the existence of correlations when communication was allowed and reflected in tandem arrivals indicates that we were not in the presence of random processes.

Determination of the optimal parasitoid‐to‐host ratio for efficient mass‐rearing of the parasitoid, Sclerodermus pupariae (Hymenoptera: Bethylidae)

AbstractSclerodermus pupariae Yang et Yao (Hymenoptera: Bethylidae) is used as a potential biocontrol agent for several buprestid and cerambycid larvae. This study aimed to enhance the efficiency of mass‐rearing of this parasitoid by investigating the fitness gain of this bethylid wasp, including the proportion of successful parasitism and development, brood size, sex ratio, proportion of winged female offspring, body size and longevity of female offspring, under eight different maternal parasitoid density treatments using Thyestilla gebleri Faldermann as host in the laboratory. The results indicated that the foundress densities did not affect the parasitism or emergence rate of this parasitoid. Brood size of the parasitoids increased significantly when the number of maternal wasps ranged from one to four. However, further increases in foundress number did not affect the parasitoid brood size. The sex ratios of S. pupariae were always female‐biased. The proportions of male in the progeny colonies were <10% throughout all experimental treatments. The percentage of winged female progeny was not significantly influenced by the density of adult maternal parasitoids. Body sizes of parasitoids significantly declined with increasing maternal parasitoid densities. Although the parasitoid body size reduced when maternal wasp number was higher, it could be compromised by the relatively higher number of female offspring produced. Further, more than 70% of the parasitoids remained alive when they were stored at 12°C for four months throughout the experiments. These findings suggest that exposure of four female wasps to a single host larva would result in the highest fitness of S. pupariae. Our findings might provide a new approach to enhance the efficiency of mass‐rearing of this bethylid wasp.

Lost in space? Host-finding ability of the parasitoids Lariophagus distinguendus and Anisopteromalus calandrae in empty grain storage facilities to control residual pest populations

We studied the ability of the parasitoid species Lariophagus distinguendus (Forster) and Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) to locate populations of the granary weevil Sitophilus granarius (L.) (Coleoptera: Dryophtoridae) in grain residues. Experiments were conducted under laboratory and storage-like conditions. Generally both parasitoid species were able to find hosts up to 10 m from the release spot. Under laboratory conditions with excluded air movement and a centered light source, host finding was largely random, declining with increasing distance of baits from the release spot. Under storage-like conditions, host finding was strongly reduced and was not influenced by distance. A. calandrae seems to have been influenced by positive phototaxis. L. distinguendus showed a weaker host-finding success than A. calandrae, which was increased by a higher number of wasps from 10–50 per release. This resulted in a 5-fold higher number of parasitizations. It is discussed that host finding of residual pest populations by L. distinguendus and A. calandrae in empty storages is difficult to predict and influenced by light and air conditions. Based on our results, we provide recommendations for the release of parasitoids against residual pest populations.

Microsatellite loci and genetic structure of artificial populations of Cotesia flavipes (Hymenoptera, Braconidae).

Cotesia flavipes (Cameron) is a parasitoid wasp used in the biological control of the sugarcane borer (Diatraea saccharalis) (Fabr., 1794). Studies on the genetic diversity of C. flavipes are hampered by the lack of highly polymorphic molecular markers. In this report, a set of 11 microsatellite loci were developed from an enriched library of C. flavipes. Four microsatellite loci were polymorphic and were screened in 212 C. flavipes individuals (183 females and 29 males) that were randomly sampled from seven rearing laboratory populations. The number of alleles ranged from two to three. The average inbreeding coefficient (FIS) among all laboratory populations was 0.120, indicating an excess of homozygotes. The average genetic diversity within the laboratory populations was 0.292, which is lower than the values reported for wild Cotesia spp populations. Genetic diversity was most pronounced within laboratory populations (70 to 90%). Most of the observed alleles were fixed or close to fixation. This low overall genetic diversity may have originated from a founder effect, i.e., the contribution of a small number of individuals (genes and alleles) to the formation of these populations. To our knowledge, this study is the first to provide microsatellite loci and an analysis of the genetic structure of C. flavipes. Our results suggest that new introductions of C. flavipes may increase genetic diversity and improve the efficiency of the biological control of D. saccharalis. In addition, population structure data could be used to estimate the minimum number of wasps to be imported.

Invasive Vespula Wasps Utilize Kairomones to Exploit Honeydew Produced by Sooty Scale Insects, Ultracoelostoma.

Vespula wasps are widely distributed invasive alien species that are able to reach high population densities in the 1.2 M ha of beech forests (Fuscospora spp.) of New Zealand's South Island. These endemic temperate forests have an abundance of carbohydrate-rich honeydew produced by native scale insects (Ultracoelostoma spp.). A characteristic aroma is associated with the honeydew in beech forests, which we hypothesized is the signal used by wasps to harvest the vast resources previously exploited by birds and other insects. Volatile collections were taken of black beech tree trunks with honeydew and sooty mold present, and analyzed with a gas chromatograph-mass spectrometer. Eleven compounds (benzaldehyde, benzyl alcohol, 2-phenylethyl acetate, 2-phenylethanol, phenylacetaldehyde, methyl 2-phenylacetate, ethyl 2-phenylacetate, methyl salicylate, n-octanol, octan-3-ol, and 1-octen-3-ol) were positively identified from the headspace, and were shown to elicit an electrophysiological response from Vespula vulgaris worker antennae by using electroantennography (EAG). Field trials with delta traps individually baited with these compounds confirmed wasp attraction to 8 of the 11 compounds tested, with 2-phenylethyl acetate, methyl salicylate, and octan-3-ol capturing the same numbers of wasps as the control. In later trials, attraction to a 1:1 blend of benzaldehyde and n-octanol was significantly higher (45%) than to any other treatment. Many of the chemicals identified are known to be associated with fermenting sugars, or with fungal aroma. Benzaldehyde and n-octanol are common compounds produced by many different species in nature. The ability to respond to generic signals emanating from sugar resources is likely to contribute to the success of V. vulgaris as an invasive species.

Effects of UV-B on Environmental Preference and Egg Parasitization byTrichogrammaWasps (Hymenoptera: Trichogrammatidae)

Abstract The intensity of ultraviolet (UV) radiation varies widely in space, both across the globe and over small spatial scales (a few millimeters), depending on patterns of light and shade. Gradients of UV radiation can control the movement of organisms on landscapes and how the organisms perform. It is likely that insects are at high risk from UV radiation because of their small size; radiation may penetrate significantly deeper into insect tissues than into larger organisms, thereby disproportionately affecting their performance. We investigated the effects of UV radiation on the behavior and parasitism success of the agriculturally important egg parasitoid wasp, Trichogramma spp. We found that Trichogramma preferred to move toward higher intensities of UV-B radiation and parasitized more eggs in areas with higher UV-B radiation. However, higher UV-B radiation reduced the number of adult wasps emerging from host eggs. Trichogramma reproductive behavior may, therefore, be maladaptive depending on envi...

New Reports that Monarch Butterflies (Lepidoptera: Nymphalidae,Danaus plexippusLinnaeus) are Hosts for a Pupal Parasitoid (Hymenoptera: Chalcidoidae,Pteromalus cassotisWalker)

Abstract Monarch butterflies are one of the best studied non-pest lepidopterans, serving as a model for migration, chemical ecology, and insect conservation. Despite the intensity with which the larvae and adults have been studied, the cryptic pupal stage is often difficult to study in the wild. It is perhaps due to this difficulty that researchers have largely overlooked monarchs’ interactions with a pupal parasitoid, Pteromalus cassotis. Using field experiments in the northern U.S. and observational data from wild collected pupae in the southern U.S., we report occurrences of this host-parasitoid interaction at sites Minnesota, Georgia, Oklahoma, Texas, and Wisconsin. At sites in Minnesota, rates of parasitism of experimentally placed monarch were highly variable, ranging from 60% in 2010 to 0% in 2013 and 2014. Observations of wild-collected pupae suggest that rates of parasitism may near 100% at some sites in the southern U.S. The number of wasps emerging from a single host ranged from 1–425 (mean = ...

Trapping Social Wasps (Hymenoptera: Vespidae) in Nurseries with Acetic Acid and Isobutanol

Abstract European hornet, Vespa crabro L., damages bark of nursery trees, and most vespid species can be a sting hazard to nursery personnel when nests are disturbed. We tested acetic acid and isobutanol lures in traps for V. crabro spring queens to determine the seasonality of vespid captures and compare the efficacy of patterns of trap placement in Tennessee nurseries. Forty traps in transects from nursery tree blocks into the forest captured 547 vespid queens during 2001 and 2002. These were 78.8% Vespula maculifrons (Buysson), 6.9% Vespula squamosa (Drury), 6.8% V. crabro, 4.8% Dolichovespula maculata (L.), 2.6% Vespula flavopilosa Jacobson, and 0.2% Vespula vidua (Saussure). Total worker and male wasp captures in these traps were 2525 and 28, respectively. Polistes spp. (n = 416) were also trapped. Peak queen trap catch was in April for V. crabro and V. maculifrons and in May for other Vespula. Numbers of worker wasps captured were greater within nursery blocks or at field-forest edges compared with ...

Beneficial insects attracted to native flowering buckwheats (Eriogonum Michx) in central Washington.

Native plant and beneficial insect associations are relatively unstudied yet are important in native habitat restoration programs aimed at improving conservation biological control in perennial crops such as wine grapes. Beneficial insects (predators, parasitoids, pollinators) attracted to 10 species of flowering native wild buckwheat (Eriogonum spp.) in central Washington were identified and counted on transparent sticky traps. Combining all categories of beneficial insects, the mean number per trap ranged from 48.5 (Eriogonum umbellatum) to 167.7 (Eriogonum elatum). Three Eriogonum spp. (E. elatum, Eriogonum compositum, and Eriogonum niveum) attracted significantly more beneficial insects than the lowest-ranked species. E. niveum attracted greatest numbers of bees and parasitic wasps, and E. elatum was highly attractive to predatory true bugs and beneficial flies. Blooming periods of Eriogonum spp. extended from mid April to the end of September. This study demonstrates the attraction of beneficial insects to native flowering buckwheats and suggests their potential as a component of habitat restoration strategies to improve and sustain conservation biological control in Washington viticulture.

The effect of banker plant species on the fitness of Aphidius colemani Viereck and its aphid host (Rhopalosiphum padi L.)

Banker plants, a type of open-rearing unit, are increasingly used in greenhouse crops to sustain natural enemy populations at times of low pest abundance. The most common banker plant system is a non-crop, cereal plant which supports Rhopalosiphum padi L. as an alternative host for Aphidius colemani Viereck. Although bottom-up effects of plants are known to affect natural enemies, this aspect has generally been ignored in previous investigations of banker plant efficacy. Here, we tested four cereal plant species with three varieties each to investigate host plant effects on R. padi and A. colemani. Though limited differences were observed in laboratory experiments spanning one aphid or parasitoid generation, longer greenhouse experiments spanning several generations revealed significant plant effects on both insects. R.padi performed poorly on oats (Avena sativa L.), resulting in wasps with the longest female development time, lowest emergence rates, and the lowest number of wasps produced per unit. Rye (Secale cereal L.) – intermediate in terms of aphid performance – produced a significantly male-biased wasp population with the smallest males. Conversely, R. padi placed onto either wheat (Triticum aestivum L.) or barley (Hordeum vulgare L.) performed consistently well in terms of aphid and parasitoid fitness and abundance, though neither species was obviously superior over the other. Overall, cultivars within each plant species did not significantly affect outcomes. As each plant species tested had different positive effects on aphid and parasitoid phenotypes, the potential benefits of mixing of cereal species is an area for future investigation.

Screening of Repellents against Vespid Wasps.

Vespid wasps are ecologically beneficial, but they can be a nuisance and dangerous to people due to their tendency to sting. Here, the aim was to screen samples of volatiles (i.e., essential oils and pure chemicals) for their repellency against wasps. The number of wasps (mainly Vespula vulgaris) present in a glass box with attractant and 5 µL sample was compared to the number of wasps in a similar box with attractant only. Both boxes were connected to a large glass container harboring 18–35 wasps. Among 66 tested samples, some essential oils from Lamiaceae and Asteraceae, as well as some pure natural compounds such as the monoterpenes (−)-terpinen-4-ol and isopulegol showed a significant repellency against vespids. Our results corroborate the potential of (mixtures of) volatiles in repelling these insects.

Selectivity of Old and New Insecticides and Behaviour of Vespidae Predators in Coffee Crop

Organophosphates are old agrochemicals that are toxic for wasps (Vespidae) that are predators of insect pests. However, chlorantraniliprole is the first insecticide produced from the new anthranilic diamide class, which binds to ryanodine receptor modulators. This study uses chlorpyrifos, triazophos, pyridaphenthion and new chlorantraniliprole insecticides that have not yet been extensively tested for effects on non-target organisms. Adults of the predatory wasps were exposed to concentrations of organophosphate inseticides and the most toxic was used for a behavior test. The trial area, located in the Rio Paranaíba, Minas Gerais, received two treatments: with insecticide and without insecticide. Chlorpyrifos, the most toxic insecticide, was used in the dose of 1.5L/ha. In order to evaluate the predation, the number with predation action (injuries made by the wasps) in the leaves were accounted. Behavior activities collect of nine colonies Protonectarina sylveirae, Brachigastra lecheguana, Polybia sp. and Polistes versicolor works were quantified. All colonies were in the adult phase. The colonies were observed by 12h, from 6:00 a.m. to 6:00 p.m. The number of wasps that leaved and returned to the nest, type of sources collected (glucidic foods, prey larvae, matherial for construction of the nest). The most toxic insecticide was chlorpyrifos and the most selective was chlorantraniliprole. The species and frequencies of wasps predator were: P. sylveirae (71.50%), B. lecheguana (12.00%), Polybia sp. (7.00%) and P. versicolor (1.00%). Chlor-pyrifos presented not selective and changes in the behavior to the predatory wasps.

A negative effect of a pathogen on its vector? A plant pathogen increases the vulnerability of its vector to attack by natural enemies

Plant pathogens that are dependent on arthropod vectors for transmission from host to host may enhance their own success by promoting vector survival and/or performance. The effect of pathogens on vectors may be direct or indirect, with indirect effects mediated by increases in host quality or reductions in the vulnerability of vectors to natural enemies. We investigated whether the bird cherry-oat aphid Rhopalosiphum padi, a vector of cereal yellow dwarf virus (CYDV) in wheat, experiences a reduction in rates of attack by the parasitoid wasp Aphidius colemani when actively harboring the plant pathogen. We manipulated the vector status of aphids (virus carrying or virus free) and evaluated the impact on the rate of attack by wasps. We found that vector status did not influence the survival or fecundity of aphids in the absence of parasitoids. However, virus-carrying aphids experienced higher rates of parasitism and greater overall population suppression by parasitoid wasps than virus-free aphids. Moreover, virus-carrying aphids were accepted as hosts by wasps more often than virus-free aphids, with a greater number of wasps stinging virus-carrying aphids following assessment by antennal palpations than virus-free aphids. Therefore, counter to the prevailing idea that persistent vector-borne pathogens enhance the performance of their vectors, we found that infectious aphids actively carrying a plant pathogen experience greater vulnerability to natural enemies. Our results suggest that parasitoids may contribute to the successful biological control of CYDV by disproportionately impacting virus-carrying vectors, and thus reducing the proportion of vectors in the population that are infectious.